package com.lzh.java;

/**
 * @author liuzhihao
 * @create 2021-02-24 21:26
 */

import org.junit.Test;

import java.io.*;

/**
 * 一、缓冲流之一：缓冲流的使用
 *
 * 1.缓冲流：
 * BufferedInputStream
 * BufferedOutputStream
 * BufferedReader
 * BufferedWriter
 *
 * 2.作用：提高流的读取、写入的速度
 *      提高读写速度的原因：
 *
 * 3.处理流：就是"套接"在已有的流的基础上
 */
public class BufferedTest {

    //实现非文本文件的复制
    @Test
    public void BufferedStreamtest(){
        BufferedInputStream bis = null;
        BufferedOutputStream bos = null;

        try {
            //1.造文件
            File srcFile = new File("1.jpg");
            File desFile = new File("4.jpg");

            //2.造流
            //2.1造节点流
            FileInputStream fis = new FileInputStream(srcFile);
            FileOutputStream fos = new FileOutputStream(desFile);
            //2.2造缓冲流
            bis = new BufferedInputStream(fis);
            bos = new BufferedOutputStream(fos);

            //3.复制的细节：读取，写入
            byte[] buffer = new byte[10];
            int len;
            while((len = bis.read(buffer)) != -1){
                bos.write(buffer,0,len);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            //4.资源关闭
            //要求：先关闭外层的流，再关闭内层的流
            try {
                if(bos != null)
                    bos.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                if(bis != null)
                    bis.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            //说明：关闭外层流的同时，内层流也会自动的进行关闭。关于内层流的关闭，我们可以省略。
//        fos.close();
//        fis.close();
        }


    }

    //实现文件复制的方法
    public void copyFileWithBuffered(String srcPath,String destPath){
        BufferedInputStream bis = null;
        BufferedOutputStream bos = null;

        try {
            //1.造文件
            File srcFile = new File(srcPath);
            File desFile = new File(destPath);

            //2.造流
            //2.1造节点流
            FileInputStream fis = new FileInputStream(srcFile);
            FileOutputStream fos = new FileOutputStream(desFile);
            //2.2造缓冲流
            bis = new BufferedInputStream(fis);
            bos = new BufferedOutputStream(fos);

            //3.复制的细节：读取，写入
            byte[] buffer = new byte[1024];
            int len;
            while((len = bis.read(buffer)) != -1){
                bos.write(buffer,0,len);

//                bos.flush();//刷新缓冲区
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            //4.资源关闭
            //要求：先关闭外层的流，再关闭内层的流
            try {
                if(bos != null)
                    bos.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                if(bis != null)
                    bis.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            //说明：关闭外层流的同时，内层流也会自动的进行关闭。关于内层流的关闭，我们可以省略。
//        fos.close();
//        fis.close();
        }
    }
    @Test
    public void testCopyFileWithBuffered(){
        long start = System.currentTimeMillis();

        String srcPath = "C:\\Users\\Dell\\Desktop\\1.mp4";
        String destPath = "C:\\Users\\Dell\\Desktop\\2.mp4";

        copyFileWithBuffered(srcPath,destPath);

        long end = System.currentTimeMillis();

        System.out.println("复制操作花费的时间为："+ (end - start));//828
    }

    /**
     * 使用BufferedReader和BufferedWriter实现文本文件的复制
     */
    @Test
    public void testBufferedReaderBufferedWriter(){

        BufferedReader br = null;
        BufferedWriter bw = null;
        try {
            br = new BufferedReader(new FileReader(new File("dbcp.txt")));
            bw = new BufferedWriter(new FileWriter(new File("dbcp1.txt")));

            //方式一：使用char[]数组
//            char[] cbuf = new char[1024];
//            int len;
//            while((len = br.read(cbuf)) != -1){
//                bw.write(cbuf);
//    //            bw.flush();
//            }

            //方式二：使用String
            String data;
            while((data = br.readLine()) != null){
                //方法一：
//                bw.write(data + "\n");//data中不包含换行符
                bw.write(data);//data中不包含换行符
                bw.newLine();//提供换行的操作
            }

        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if(bw != null){
                try {
                    bw.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if(br != null){
                try {
                    br.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }


    }

}
